1. Field of the Invention
The present disclosure relates to a method for securely transmitting data or digital messages simultaneously to two electronic devices.
2. Description of the Related Art
The transmission of confidential information or messages between two or more electronic devices is known to be achieved by encrypting the messages to be transmitted (and, consequently, deciphering those received) in accordance with cryptographic methods. The exchanged messages which it is desired be made secret or confidential are encrypted by applying appropriate encryption rules and using appropriate encryption keys.
Encryption methods are subdivided into symmetrical or asymmetrical methods depending on whether a message is encrypted and decrypted using a single key (symmetrical secret key) or two distinct keys (a public and a private key), respectively.
For example, one asymmetric method known is the IBE (Identity Based Encryption) method. In accordance with the IBE method, the public key of a user transmitting in an encrypted manner is obtained from the identity of the user (for example the user's tax code) and does not constitute confidential information. The user's private key is secret and is assigned to each user by a unique central authority denominated Trusted Authority TA. Conventional methods for the generation of the public and private keys and the operating characteristics of the trusted authority TA are known to those skilled in the art.
In some applications, it may be useful to securely transmit a message, using the IBE method, simultaneously to two electronic devices.
In accordance with known encryption techniques, the message to be transmitted to both devices is encrypted, sequentially, once with the public key corresponding to the first device and a second time with that corresponding to the second device.
In order to restore the original message, the received encrypted message is, to begin with, decrypted firstly with the private key corresponding to the second device. Subsequently, the result of such decryption is sent to the first device, which decrypts it using its own private key, thus restoring the original message.
In this way, the encrypted message may be decrypted only by using subsequent decryption operations carried out by both devices. Indeed, a single device does not have sufficient information to decrypt the message in question.
In particular, it is observed that the transmitted message, which has been encrypted using encryption keys according to a pre-established order, may only be restored by applying the decryption keys in reverse order with respect to the corresponding encryption keys. That constitutes a limitation for the known encryption methods.
Furthermore, the message to be transmitted simultaneously to two devices requires an encryption step that is taxing from the computational point of view.